Keying problems

[fxfellow]

Hello, people!

I’m working a kids TV series that has a LOT of keying b/c of virtual sets — anyways, I’m used to the REALLY excellent Primatte/Composite wizard package (for AFX), and I’m now trying to key using combustion. Yes, I can get a clean matte, but the problem is that the edges SHIMMY! My god, it looks like a wave of marching ants along their outline!!! Is there ANY way ANY of you know to prevent this? Can’t combustion keep a still matte?
Also, I’ve read that Combustion is capable of “lightwrapping,” is this true? And I don’t mean lightwrapping by making a dupe of the bgnd, and utilizing the keying matte inverted and scaled down to overlay over the original comp of the keyed foreground and background.
Any help on the keying shimmy would be a blessing!!!
Thanks.

[Anonymous]

hmm, yes, ants problem is usually connected to fields material so be sure you check your footage and process method to fields. Using erode or/and shrink might help but if hair detail is important you might want work on it more.

As for Lightwrap I don’t think its a push button solution in Combustion unless you are using some plugin to this. I think one is composite wizard for AFX but it works in Combustion to. Anyway the way I do it is copy background do serious blurr on it then put that over your final composite through matt edge like matt.
Edge matt can be done in more ways but one is to use edgedetection on your key alpha (should be on the inner or centre to the edge). Or method I use sometimes to is to blurr the original matt and the exclude (math ops) that from the original mate and voila edge ring.

I hope that something in here helps you out,
Christian 😛

[ram]

hi fx fellow,

This is ram here,

i read ur question ,wat u mentioned is a most common problem will happen
always when is footage is shooted without a power full back kicker light.
wat happenes is the blue spill will be all over the edges.so when u key the footage due to the grains present in the spill area -edges some of the grains which has blue on it will be taken off -results in a edge jittering matte.

here is wat i would like to suggest u is the process i do for my composite
is that i apply a blur over the image b4 keying that makes the grains in the
image to smooth then i do keying i will get a smooth edged matte
then using the matte thru set matte option i composite the imageover the bg.that works i hope.

any way ,try it n reply me the result.
Thanks
Ram Cr 8)

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